Spoilers are typically provided on the upper aerodynamic surface of an aircraft wing, between the main fixed wing box and the trailing edge flaps. The performance of the flaps can be improved by attaching them to the fixed wing box by drop hinge mechanisms. This allows the flaps to be deployed in both aft and downward directions and to be rotated downwardly (or “drooped”). When the flaps are deployed in this way, gaps are formed between the trailing edges of the spoilers and the leading edges of the flaps. Small air gaps in these regions improve lift when compared to conventional Fowler flaps. However, if these gaps are too large and the continuity of the upper aerodynamic surface is not maintained, then the performance of the flaps is reduced. To control the size of these gaps, the spoilers are rotated downwardly (or “drooped”) when the flaps are deployed (e.g. during take-off).
In normal operation, for example when the aircraft moves from the take-off configuration to the cruise configuration, the drooped spoilers are retracted to clear the way for the flaps to be retracted to their stowed (or cruise) positions. However, in the case of failure of the spoiler actuator control system, the spoiler can be locked down in the maximum droop position, thus causing jamming between the leading edge of the flap and the trailing edge of the spoiler when the flap is retracted. If the flap cannot retract to its cruise position, the performance of the wing deteriorates significantly. Therefore, a method of freeing the spoiler from the actuator is needed to allow the flap to retract even when the actuator control system fails.